Gas Sensor

Abstract

To provide a gas sensor with which it is possible to prevent the characteristics of a sensor element from changing as will be caused by the deformation of a substrate.SOLUTION: Provided is a gas sensor comprising: a sensor element having a frame-shaped holding part, a sensitive film that is disposed at a first opening on the first direction side of the holding part, and a pair of electrodes that are connected to the sensitive film; and a substrate on which the sensor element is mounted. The sensor element has at least a pair of electrode pads that are arranged at a circumferential edge of the first opening in the holding part, which is a non-angle circumferential edge not including corners of the sensor element, and that are electrically connected to the pair of electrodes. The sensor element is connected to the substrate via at least the electrode pads, with the pair of electrode pads postured to face the substrate side.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a gas sensor. [Background technology]

[0002] A gas sensor is a device for detecting, for example, gas leakage, and is mounted in home appliances, industrial equipment, environmental monitoring equipment, etc. For example, as described in Patent Document 1, a gas sensor has a sensor element and a substrate on which the sensor element is mounted.

[0003] A conventional sensor element has a sensor element whose physical properties change in response to the gas concentration in the atmosphere, etc., and electrodes for extracting the change in physical properties as an electrical signal. The substrate is made of a printed circuit board or the like, and is fixed to the module substrate of various electronic devices while holding the sensor element and the control element that controls it.

[0004] In conventional gas sensors, deformation such as warping can occur in the substrate due to the effects of temperature and humidity, or the propagation of stress from other substrates. In such gas sensors, the stress caused by the warping of the substrate is transmitted to the sensor element, causing fluctuations in the distance between the electrodes of the sensor element, which in turn causes fluctuations in gas sensor characteristics such as sensitivity and reduces the detection accuracy of the gas sensor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 2019-120698 Summary of the Invention [Problem to be solved by the invention]

[0006] The present disclosure provides a gas sensor that can prevent fluctuations in the characteristics of a sensor element due to deformation of a substrate. [Means for solving the problem]

[0007] A gas sensor according to a first aspect of the present disclosure includes: a sensor element including a frame-shaped holding portion, a sensitive membrane disposed in a first opening on a first direction side of the holding portion, and a pair of electrodes connected to the sensitive membrane; a substrate on which the sensor element is mounted, the sensor element is disposed in a peripheral non-corner portion of the holding portion that is a peripheral portion of the first opening, excluding corner portions of the sensor element, and has at least a pair of electrode pad portions electrically connected to a pair of the electrodes; The sensor element is connected to the substrate via at least the pair of electrode pads, with the electrode pads facing the substrate.

[0008] In this gas sensor, the sensor element is connected to the substrate via electrode pads, with the electrode pads facing the substrate. Therefore, unlike conventional technologies in which the electrode pads face away from the substrate, this gas sensor does not have a connection portion for connecting to the substrate, such as a wire-bonding connection portion, on the surface of the sensor element facing away from the substrate. This avoids the problem of such a surface not adapting to substrate deformation. Furthermore, the electrode pads connected to the substrate are located in non-corner peripheral areas, avoiding the corners of the sensor element, thereby preventing stresses associated with deformations such as warping of the substrate from being transmitted to the sensor element. Therefore, this gas sensor effectively prevents variations in the inter-electrode distance and characteristics of the sensor element due to substrate deformation. Furthermore, even though the surface of the sensor element facing away from the substrate does not adapt to substrate deformation as well as conventional technologies, it is possible to prevent the problem of large stress acting on the connection between the sensor element and the substrate.

[0009] Furthermore, for example, the sensor element may include a heat source that heats the sensitive film, and a heat source pad portion that is disposed in the non-corner peripheral portion and is electrically connected to the heat source, The sensor element may be connected to the substrate via at least the pair of electrode pad portions and the heat source pad portion, with the pair of electrode pad portions and the heat source pad portion facing the substrate side.

[0010] This type of gas sensor enables highly accurate detection by controlling the temperature of the sensitive film with a heat source. Furthermore, the heat source pads for ensuring electrical connection between the substrate and the heat source are also located on non-cornered peripheral edges of the surface facing the substrate, similar to the electrode pads, which effectively prevents stresses caused by deformations such as warping of the substrate from being transmitted to the sensor element.

[0011] Furthermore, for example, at least two of the pair of electrode pad portions and heat source pad portions may be arranged such that a center-to-center distance is a first length along a second direction perpendicular to the first direction in the peripheral edge portion, The first length may be 60% or less of an element length, which is the length of the sensor element in the second direction. Furthermore, for example, the first length may be 20% or less of an element length, which is the length of the sensor element in the second direction.

[0012] When the total number of electrode pads and heat source pads is three or more, arranging two or more pads along the second direction, which is perpendicular to the first direction, avoids distributing the pads on three or more sides of the holder, thereby preventing stress from being transmitted from the substrate to the sensor element. Also, by setting the center-to-center distance of the pads to a predetermined ratio or less of the element length, the problem of stress caused by deformation such as warping of the substrate being transmitted to the sensor element can be effectively prevented.

[0013] Furthermore, for example, the sensor element may include a plurality of the sensitive films, a plurality of pairs of the electrodes corresponding to the respective sensitive films, and at least a plurality of pairs of the electrode pad portions, all of which are disposed in the non-corner peripheral portion and electrically connected to the plurality of pairs of the electrodes, The sensor element may be connected to the substrate via at least the electrode pad portions, with the plurality of pairs of electrode pad portions facing the substrate side.

[0014] A gas sensor having multiple sensitive films can perform highly accurate detection by, for example, using the output of one of the sensitive films as a reference value. In addition, by arranging multiple pairs of electrode pads at non-corner portions of the periphery of the surface facing the substrate, it is possible to effectively prevent the problem of stress caused by deformation such as warping of the substrate being transmitted to the sensor element.

[0015] Furthermore, for example, the plurality of pairs of electrode pad portions may be arranged in inter-membrane portions that are portions of the peripheral non-corner portion between the plurality of sensitive membranes.

[0016] In a gas sensor in which an electrode pad portion is arranged in the inter-membrane portion, the connection points between the substrate and the sensor element are concentrated in a position away from the corners, which more effectively prevents the problem of stress caused by deformation such as warping of the substrate being transmitted to the sensor element.

[0017] Furthermore, for example, the sensor element may have a dummy pad portion disposed in the non-corner peripheral portion and insulated from other portions of the sensor element, The sensor element may be connected to the substrate via at least the pair of electrode pad portions and the dummy pad portion, with the pair of electrode pad portions and the dummy pad portion facing the substrate side.

[0018] A sensor element that connects to a substrate using dummy pads in addition to electrode pads can improve the connection strength between the sensor element and the substrate. Furthermore, like the electrode pads, the dummy pads are also located on non-corner peripheral edges of the surface facing the substrate, which effectively prevents stress caused by deformation such as warping of the substrate from being transmitted to the sensor element.

[0019] Furthermore, for example, the sensor element may include a plurality of the sensitive films, a plurality of pairs of the electrodes corresponding to the respective sensitive films, and at least a plurality of pairs of the electrode pad portions, all of which are disposed in the non-corner peripheral portion and electrically connected to the plurality of pairs of the electrodes, The sensor element may have a dummy pad portion disposed in an inter-membrane portion that is a portion between the plurality of sensitive films in the peripheral non-corner portion and is insulated from other portions of the sensor element, The sensor element may be connected to the substrate via at least the electrode pad portions and the dummy pad portions, with a plurality of pairs of the electrode pad portions and the dummy pad portions facing the substrate side.

[0020] When the sensor element has multiple sensitive films, by placing the dummy pad portion in the inter-film portion, which is the portion between the sensitive films, it is possible to effectively prevent the problem of stress caused by deformation such as warping of the substrate being transmitted to the sensor element while increasing the bonding strength between the sensor element and the substrate.

[0021] A gas sensor according to a second aspect of the present disclosure includes a sensor element having a frame-shaped holding portion, a sensitive membrane arranged in a first opening on a first direction side of the holding portion, a pair of electrodes connected to the sensitive membrane, and a heat source that heats the sensitive membrane; a substrate on which the sensor element is mounted, the sensor element is disposed on a peripheral edge of the first opening in the holding portion and includes at least a pair of electrode pad portions electrically connected to the pair of electrodes, and a heat source pad portion is disposed on the peripheral edge and electrically connected to the heat source, the sensor element is connected to the substrate via at least the pair of electrode pad portions and the heat source pad portion, with the pair of electrode pad portions and the heat source pad portion facing the substrate side; At least two of the pair of electrode pad portions and heat source pad portions are arranged such that a center-to-center distance is a first length along a second direction perpendicular to the first direction in the peripheral edge portion, The first length is 60% or less of an element length, which is the length of the sensor element in the second direction.

[0022] In this gas sensor, the sensor element is connected to the substrate via electrode pads, with the electrode pads facing the substrate. Therefore, unlike conventional technologies in which the electrode pads face away from the substrate, this gas sensor does not have a connection part to the substrate, such as a wire-bonding connection, on the surface of the sensor element facing away from the substrate. This avoids the problem of such a surface not adapting to substrate deformation. Furthermore, by arranging two or more electrode pads and heat source pads connected to the substrate along a second direction perpendicular to the first direction, it is possible to avoid distributing the pads on three or more sides of the sensor element and prevent stress from being transmitted from the substrate to the sensor element. Furthermore, by setting the center-to-center distance of the pads to a predetermined ratio or less of the element length, it is possible to effectively prevent stress from being transmitted to the sensor element due to deformation such as warping of the substrate. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a schematic perspective view of a gas sensor according to a first embodiment. [Figure 2] FIG. 2 is a conceptual diagram showing a surface of the sensor element of the gas sensor shown in FIG. 1 that faces the substrate. [Figure 3] FIG. 3 is a schematic perspective view of a sensor element included in the gas sensor shown in FIG. [Figure 4] FIG. 4 is an exploded perspective view of the sensor element shown in FIG. [Figure 5] FIG. 5 is a plan view of the sensor element shown in FIG. [Figure 6] FIG. 6 is a side view of the sensor element shown in FIG. [Figure 7] FIG. 7 is a cross-sectional view of the sensor element shown in FIG. [Figure 8] FIG. 8 is a conceptual diagram showing a state in which the sensor element in the gas sensor shown in FIG. 1 is offset in the direction opposite to the mounting direction. [Figure 9] FIG. 9 is a schematic perspective view of the gas sensor according to the second embodiment. [Figure 10]FIG. 10 is a schematic perspective view of the gas sensor according to the third embodiment. [Figure 11] FIG. 11 is a schematic perspective view of the gas sensor according to the fourth embodiment. [Figure 12] FIG. 12 is a perspective view showing gas sensors according to an example and a comparative example. [Figure 13] FIG. 13 is a graph showing the measurement results of the displacement in the Z direction generated in the sensor elements of the gas sensors according to the example and the comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0024] Hereinafter, the present invention will be described based on the embodiments shown in the drawings.

[0025] Fig. 1 is a schematic perspective view showing a gas sensor 101 according to a first embodiment. The gas sensor 101 is a device for detecting, for example, gas leakage, and is mounted in home appliances, industrial equipment, environmental monitoring equipment, etc. As shown in Fig. 1, the gas sensor 101 has a sensor element 10 and a substrate 80 on which the sensor element 10 is mounted.

[0026] As shown in Figure 1, the sensor element 10 has a frame-shaped holding portion 12 including a base 20, a sensitive membrane 60 arranged in a first opening 13 on the first direction D1 (negative direction of the Z axis) side of the holding portion 12, and a pair of electrodes 50a, 50b (see Figure 5) connected to the sensitive membrane 60.

[0027] 2 is a perspective view of the sensor element 10 in the gas sensor 101 shown in FIG. 1, observed from the substrate 80 side (the negative Z-axis direction side) through the substrate 80. As shown in FIG. 2, the sensor element 10 has at least one pair (one pair in the sensor element 10) of electrode pad portions 71a and two heat source pad portions 72b. The electrode pad portions 71a, 71b and the heat source pad portions 72a, 72b are arranged on the peripheral portion 14 of the first opening 13 in the holder 12.

[0028] Fig. 8 is a conceptual diagram in which the sensor element 10 is offset in the direction opposite to the mounting direction (positive Z-axis direction) with respect to the substrate 80 in the gas sensor 101 shown in Fig. 1. As shown in Fig. 8, substrate pad portions 81 for connecting and fixing the sensor element 10 are formed on a mounting surface 80a of the substrate 80, which is the surface facing the sensor element 10.

[0029] The substrate pad portion 81 of the substrate 80 shown in Fig. 8 is provided to correspond to the electrode pad portions 71a, 71b and heat source pad portions 72a, 72b of the sensor element 10 shown in Fig. 2. As can be seen from Figs. 1, 2 and 8, the sensor element 10 is connected to the substrate 80 via at least the electrode pad portions 71a, 71b and the heat source pad portions 72a, 72b, with the pair of electrode pad portions 71a, 71b and the heat source pad portions 72a, 72b facing the substrate 80 side.

[0030] The sensor element 10 can be mounted on the substrate 80 by, for example, flip-chip bonding, but the method of mounting the sensor element 10 on the substrate 80 may be a method other than flip-chip bonding. Also, the electrical connection between the substrate pad portion 81 and the electrode pad portions 71a, 71b and the heat source pad portions 72a, 72b can be exemplified by, for example, ACP connection, ACF connection, ultrasonic connection, etc., but other connection methods may also be used.

[0031] As shown in FIG. 1, in the description of the gas sensor 101 and the sensor element 10, the mounting direction of the sensor element 10 (the normal direction of the mounting surface 80a) is the Z-axis direction, the direction perpendicular to the Z-axis direction and in which the electrode pad portion 71a and the heat source pad portion 72a or the electrode pad portion 71b and the heat source pad portion 72b are aligned is the Y-axis direction, and the direction perpendicular to the Z-axis direction and the Y-axis direction is the X-axis direction.

[0032] 3 is a perspective view of the sensor element 10 included in the gas sensor 101, as viewed from the negative Z-axis direction. The sensor element 10 is a thermal conduction sensor element that detects gases such as CO2, H2, He, or CO. The sensor element 10 has a substantially rectangular parallelepiped outer shape, and is substantially rectangular when viewed in a direction parallel to the mounting direction (Z-axis direction).

[0033] Fig. 4 is an exploded perspective view of the sensor element 10. As shown in Fig. 4, the sensor element 10 has a base 20, three insulating films 30a, 30b, and 30c, a heat source 40, electrodes 50a and 50b, a sensitive film 60, electrode pad portions 71a and 71b, and heat source pad portions 72a and 72b.

[0034] 3, the sensor element 10 has an air bridge structure in which a frame-shaped holding portion 12 fixes the sensitive film 60 and the like in a doubly supported beam shape. The holding portion 12 includes the base 20 shown in FIG. 4 and the insulating film peripheral portions 36 of the insulating films 30a to 30c.

[0035] As shown in FIG. 4, the base 20 has a hollow columnar or rectangular ring shape. The base 20 has a square shape when viewed from the Z-axis direction. However, the planar shape of the base 20 is not limited to this and may be rectangular or another polygon. The height of the base 20 is not limited to the height shown in FIG. 4. At least a portion of the insulating film peripheral portion 36 of the insulating films 30a-30c and at least a portion of each of the pad portions 71a, 71b, 72a, 72b, etc. are arranged to overlap the base peripheral portion 22, which is the peripheral portion of the base 20 on the first direction D1 (negative direction of the Z-axis) side.

[0036] 3, the base 20 has a mechanical strength sufficient to support the sensitive film 60 disposed in the first opening 13 of the holder 12, the insulating film main body 31 of the insulating films 30a to 30c, etc. The base 20 is preferably made of a material suitable for microfabrication such as etching. Examples of materials that can be used to form the base 20 include a silicon single crystal substrate, a sapphire single crystal substrate, a ceramic substrate, a quartz substrate, and a glass substrate.

[0037] The insulating films 30a to 30c shown in FIG. 4 are made of an insulating material, have substantially the same planar shape, and are arranged to overlap along the Z-axis direction so that the positions and orientations of the insulating films 30a to 30c are consistent when viewed from the Z-axis direction (see FIG. 6, a side view of the sensor element 10). The insulating films 30a to 30c are made of films and are fabricated by a known film formation method (such as sputtering or CVD). The insulating films 30a, 30b, and 30c are stacked in this order on the base peripheral portion 22 of the base 20 (see FIG. 4). As shown in FIG. 4, the insulating films 30a to 30c each have an insulating film main body portion 31, an insulating film beam portion 32, an insulating film peripheral portion 36, and a hole portion 37.

[0038] As shown in FIG. 4, the insulating film main body 31 has a substantially rectangular shape when viewed from the Z-axis direction. The insulating film main body 31 is disposed in the first opening 13 (see FIG. 3) of the frame-shaped holding portion 12, and is located inside the inner periphery of the base 20. The shape of the insulating film main body 31 is not limited to the shape shown in FIG. 4, and may be rectangular, another polygonal shape, circular, elliptical, or the like. The insulating film peripheral portion 36 has a substantially ring shape corresponding to the shape of the base 20, and at least a portion of it overlaps with and connects to the base peripheral portion 22 when viewed from the Z-axis direction. The insulating film peripheral portion 36 is disposed to surround the outer periphery of the insulating film main body 31, with a predetermined gap between it and the insulating film main body 31.

[0039] As shown in Fig. 4, the insulating film beam portions 32 are located between the insulating film main body portion 31 and the insulating film peripheral portion 36, and connect four corners of the insulating film main body portion 31 to four corners of the insulating film peripheral portion 36, respectively. As shown in Fig. 3, the insulating film beam portions 32 support the insulating film main body portion 31 in the first opening 13 of the base 20. As shown in Fig. 4, four holes 37 separated by four insulating film beam portions 32 are formed between the insulating film main body portion 31 and the insulating film peripheral portion 36. The number of insulating film beam portions 32 in the insulating films 30a to 30c is not limited to four.

[0040] The thickness of each of the insulating films 30a to 30c is not particularly limited, but is, for example, 0.05 to 1.5 μm. Examples of materials that can form the insulating films 30a to 30c include silicon oxide and silicon nitride. The insulating films 30a to 30c are preferably formed from the same material. This is because this improves adhesion at the interfaces between the insulating films 30a to 30c and ensures the mechanical strength of the insulating films 30a to 30c. The insulating films 30a to 30c may be formed from different materials. The insulating films 30a to 30c may have the same thickness or different thicknesses.

[0041] As shown in FIG. 4, the heat source 40 is disposed between the insulating film 30b and the insulating film 30c (see FIG. 7). The heat source 40 can heat the sensitive film 60 to a predetermined temperature (operating temperature) when detecting a target gas. The heat source 40 is composed of a conductive film such as a resistor, and is fabricated by a known film formation method. The heat source 40 has a heat source body 41 and lead-out portions 42 and 43.

[0042] As shown in FIG. 4, the heat source body 41 has a meander pattern and is disposed between the insulating film body 31 of the insulating film 30b and the insulating film body 31 of the insulating film 30c. By forming the heat source body 41 in a meander pattern, the sensitive film 60 can be heated uniformly. Furthermore, since the sensor element 10 has an air bridge structure, the power consumption of the heat source 40 can be reduced when heating the sensitive film 60. The shape of the heat source 40 is given by, for example, etching (patterning). The same applies to the shapes of the insulating films 30a to 30c, etc.

[0043] 5 is a conceptual diagram showing the wiring structure of sensor element 10, and is a plan view of sensor element 10 as viewed from the negative Z-axis direction. As shown in Fig. 5, lead-out portion 42 of heat source 40 is connected to one end of heat source body 41 and extends to peripheral edge portion 14 of holding portion 12 between insulating film 30a and insulating film 30b, via one of insulating film beam portions 32. Lead-out portion 43 is connected to the other end of heat source body 41 and extends to peripheral edge portion 14 of holding portion 12 between insulating film 30a and insulating film 30b, via the other insulating film beam portion 32.

[0044] The heat source 40 is preferably made of a conductive material with a relatively high melting point. Examples of materials that can be used to make the heat source 40 include molybdenum, platinum, gold, tungsten, tantalum, palladium, iridium, or alloys containing one or more of the above elements. Platinum is particularly preferred because it allows for high-precision dry etching (such as ion milling) and has high corrosion resistance. When the heat source 40 is made of platinum, it is preferable to form an adhesive layer made of titanium or the like between the insulating film 30a and the heat source 40.

[0045] As shown in Fig. 4, the electrodes 50a and 50b each have a curved shape and are disposed between the insulating film 30b and the sensitive film 60 (see Fig. 7). The electrodes 50a and 50b are used to extract changes in the physical properties (resistance value) of the sensitive film 60 as electrical signals. The electrodes 50a and 50b are made of, for example, a conductive film and are fabricated by a known film formation method.

[0046] As shown in Fig. 4, the electrodes 50a and 50b are disposed opposite each other with a predetermined gap between the insulating film main body 31 of the insulating film 30b and the sensitive film 60. As shown in Fig. 5, a portion of the electrode 50a passes between the insulating film beam portion 32 and the sensitive film beam portion 62 and extends to the position of the peripheral edge portion 14 of the holding portion 12. Similarly to a portion of the electrode 50a, a portion of the electrode 50b passes between the insulating film beam portion 32 and the sensitive film beam portion 62 (however, a portion different from that passed by the electrode 50a) and extends to the position of the peripheral edge portion 14 of the holding portion 12. In Fig. 5, the electrodes 50a and 50b are displayed with a dot pattern in order to distinguish them from the heat source 40.

[0047] The electrodes 50a, 50b are preferably made of a conductive material with a relatively high melting point, such as molybdenum, platinum, gold, tungsten, tantalum, palladium, iridium, or an alloy containing one or more of the above elements.

[0048] As shown in Fig. 3, the sensitive film 60 has the property of changing its heat dissipation characteristics in response to the gas concentration in the atmosphere, and also changing its resistance value in response to the change in heat dissipation characteristics. The sensitive film 60 is made of a thermistor film, a platinum film, or the like, and is fabricated by a known film formation method. Examples of materials that can be used to form the thermistor film include composite metal oxides, amorphous silicon, polysilicon, and germanium.

[0049] 4, the sensitive film 60 has a sensitive film main body 61 and four sensitive film beams 62. The sensitive film main body 61 has a planar shape corresponding to (preferably the same planar shape as) the insulating film main body 31 of the insulating films 30a to 30c. The sensitive film beams 62 have a planar shape corresponding to (preferably the same planar shape as) the insulating film beams 32 of the insulating films 30a to 30c. Therefore, in the Z-axis direction, the sensitive film main body 61 is disposed at a position corresponding to the insulating film main body 31, and the sensitive film beams 62 are disposed at positions corresponding to the insulating film beams 32.

[0050] The sensitive film main body 61 is disposed so as to be in contact with the electrodes 50a and 50b and is electrically connected to the electrodes 50a and 50b. The sensitive film 60, the electrodes 50a and 50b are integrally disposed between the insulating film 30b and the insulating film 30c (see FIG. 4).

[0051] The electrode pads 71a and 71b shown in Fig. 4 are electrically connected to a pair of electrodes 50a and 50b. As shown in Fig. 5, the electrode pad 71a is electrically connected to an end of the electrode 50a at the peripheral edge 14 of the holding part 12 via a through-hole (not shown). Similarly to the electrode pad 71a, the electrode pad 71b is also electrically connected to an end of the electrode 50b at the peripheral edge 14 of the holding part 12 via a through-hole (not shown).

[0052] 3 and 5, the electrode pad portions 71a, 71b are arranged in the peripheral portion 14 of the first opening 13 in the holding portion 12, in a peripheral non-corner portion 14a excluding the corner portion 11 of the sensor element 10. More specifically, the peripheral portion 14 of the first opening 13 in the holding portion 12 is a portion that is farther away from the center 60a of the sensitive portion 60 than the hole portion 37 of at least one insulating film 30a and the outer edge extension line 37a of the hole 37, when viewed from the negative direction of the Z axis, and includes the base peripheral portion 22 and the insulating film peripheral portions of the insulating films 30a to 30c shown in FIG.

[0053] 3 and 5, the corner portions 11 of the sensor element 10 are the peripheral portions of the four corners of the sensor element 10, and more specifically, include the portions that are spaced apart from the center 60a of the sensitive membrane 60 by the two outer edge extension lines 37a. The electrode pad portions 71a and 71b are arranged in the non-corner peripheral portions 14a of the peripheral portion 14, excluding the corner portions 11. In FIG. 3, the non-corner peripheral portions 14a are shown with a dot pattern to make the area of ​​the non-corner peripheral portions 14a easier to understand. In addition, in the case of the sensor elements 210, 310, and 410 shown in FIGS. 9 to 11, which have multiple first openings 13 and sensitive portions 60, the portions between the two sensitive membranes 60 in the second direction D2 (Y-axis direction) are not included in the corner portions 11, even if they are portions that are spaced apart from the center 60a of the sensitive membranes 60 by the two outer edge extension lines 37a.

[0054] The heat source pad portions 72a and 72b shown in Fig. 4 are electrically connected to the heat source 40. As shown in Fig. 5, the heat source pad portion 72a is electrically connected to the end of the draw-out portion 42 of the heat source 40 at the peripheral portion 14 of the holding portion 12 via a through-hole (not shown). Similarly to the heat source pad portion 72a, the heat source pad portion 72b is also electrically connected to the end of the draw-out portion 43 at the peripheral portion 14 of the holding portion 12 via a through-hole (not shown).

[0055] 3 and 5, like the electrode pad portions 71a and 71b, the heat source pad portions 72a and 72b are also arranged in the peripheral non-corner portion 14a of the holder 12. In the sensor element 10, the four pad portions 71a, 71b, 72a, and 72b, each consisting of the electrode pad portions 71a and 71b and the heat source pad portions 72a and 72b, are arranged two by two on two of the four sides included in the peripheral non-corner portion 14a that are parallel to each other.

[0056] 5, at least two of the pair of electrode pads 71a, 71b and heat source pads 72a, 72b are preferably arranged along a second direction D2 (Y-axis direction) perpendicular to a first direction D1 (negative Z-axis direction) in the peripheral portion 14 so that the center-to-center distance is a first length L1. More specifically, the electrode pad 71a and the heat source pad 72a are arranged on one of the four sides included in the peripheral non-corner portion 14a, which is located on the negative X-axis side of the center 60a of the sensitive film 60 and extends in the Y-axis direction. Furthermore, the electrode pad 71b and the heat source pad 72b are arranged on one of the four sides included in the peripheral non-corner portion 14a, which is located on the positive X-axis side of the center 60a of the sensitive film 60 and extends in the Y-axis direction.

[0057] 5, the first length L1, which is the center-to-center distance between the electrode pad portion 71b and the heat source pad portion 72b, is preferably 60% or less of the element length L2, which is the length in the second direction D2 (Y-axis direction) of the sensor element 10. The center-to-center distance between the electrode pad portion 71a and the heat source pad portion 72a is also the same as the center-to-center distance between the electrode pad portion 71b and the heat source pad portion 72b.

[0058] When the total number of electrode pad portions 71a, 71b and heat source pad portions 72a, 72b is three or more, arranging two or more pad portions 71a, 71b, 72a, 72b along the second direction D2 can avoid distributing the pad portions 71a, 71b, 72a, 72b on three or more sides of the holding portion 12. Even if the substrate 80 is deformed when the sensor element 10 is mounted on the substrate 80, the stress transmitted from the substrate 80 to the sensor element 10 can be reduced. Furthermore, by setting the first length L1, which is the center-to-center distance between the pad portions 71a, 72a and the pad portions 71b, 72b arranged along the second direction D2, to a predetermined ratio or less of the element length L2, the problem of stress due to deformation of the substrate 80 being transmitted to the sensor element 10 can be effectively prevented compared to, for example, distributing the pad portions on the four corners 11 of the sensor element 10.

[0059] Furthermore, from the viewpoint of reducing the stress transmitted from the substrate 80 to the sensor element 10, it is also preferable that the first length L1, which is the center-to-center distance between the pad portions 71a, 72a and the pad portions 71b, 72b, is 20% or less of the element length L2 (see FIG. 11, etc.). Note that setting the first length L1 to a predetermined ratio or less with respect to the element length L2 will be described in detail later with reference to examples.

[0060] The electrode pad portions 71a, 71b and the heat source pad portions 72a, 72b are formed on the insulating film peripheral portion 36 of the insulating film 30a by, for example, plating, lift-off, metal paste printing, or other methods.

[0061] 1 and 8 is configured by a printed circuit board, etc. The substrate 80 is configured by a plate body having a substantially flat plate shape, but may also be, for example, a package substrate for incorporating the sensor element 10.

[0062] As shown in FIG. 1, the sensor element 10 is fixed to a substrate 80 by connecting electrode pad portions 71a, 71b and heat source pad portions 72a, 72b shown in FIG. 3 etc. to a substrate pad portion 81 shown in FIG.

[0063] 1, 2, 8, etc., in the gas sensor 101 according to the first embodiment, the sensor element 10 is connected to the substrate 80 via the electrode pad portions 71 with the electrode pad portions 71a and 71b facing the substrate 80. Unlike conventional techniques in which the electrode pad portions face away from the substrate, the gas sensor 101 does not require a connection portion to the substrate, such as a bonding wire, to be formed on the surface of the sensor element 10 facing away from the substrate 80 (the surface on the positive Z-axis direction). Therefore, in the gas sensor 101, the surface on the positive Z-axis direction of the sensor element 10 is not constrained to the substrate 80, and problems caused by this surface not following the deformation of the substrate 80 are avoided.

[0064] 3 and 5, the electrode pads 71a, 71b and the heat source pads 72a, 72b connected to the substrate 80 are arranged in the peripheral non-corner portion 14a, avoiding the corners 11 of the sensor element 10. This prevents stress caused by deformation such as warping of the substrate 80 from being transmitted to the sensor element 10. Therefore, such a gas sensor 101 can effectively prevent changes in the inter-electrode distance of the sensor element 10 caused by deformation of the substrate 80 and the resulting fluctuations in characteristics. Furthermore, even if the surface of the sensor element 10 facing away from the substrate 80 does not follow the deformation of the substrate 80 as much as in the past, it is possible to prevent the problem of large stress acting on the connection point between the sensor element 10 and the substrate 80 and prevent damage to the connection point.

[0065] Therefore, the gas sensor 101 can prevent fluctuations in the characteristics of the sensor element 10 due to deformation of the substrate 80, and can perform detection with high accuracy even under conditions where deformation of the substrate 80 occurs due to temperature or humidity.

[0066] Second embodiment FIG. 9 is a schematic perspective view showing a sensor element 210 included in the gas sensor according to the second embodiment. The sensor element 210 according to the second embodiment has a plurality of (two in FIG. 9 ) sensitive films 60 and has a structure in which two sensor elements 10 shown in FIG. 3 and the like are connected in the Y-axis direction. However, the sensor element 210 has substantially the same sensitive films 60, electrodes 50a, 50b, and heat source 40 as the sensor element 10 (although the wiring shapes of the electrodes 50a, 50b and the lead-out portions 42, 43 in the peripheral portion 214 are slightly different). Therefore, the description of the sensor element 210 will focus on the differences from the sensor element 10, and commonalities with the sensor element 10, such as the internal structure shown in FIG. 4, will be omitted.

[0067] 9, the sensor element 210 has a plurality of (two in the embodiment) sensitive films 60, a plurality of pairs (two in the embodiment) of electrodes 50a, 50b (see FIG. 4) corresponding to the respective sensitive films 60, and at least a plurality of pairs (two in the embodiment) of electrode pad portions 271a, 271b electrically connected to the plurality of pairs (two in the embodiment) of electrodes 50a, 50b. Also, although some parts are not shown in FIG. 9 because they are internal structures, the sensor element 210 has a plurality of (two in the embodiment) heat sources 40 corresponding to the respective sensitive films 60, and at least a plurality of pairs (two in the embodiment) of heat source pad portions 272a, 272b electrically connected to the heat sources 40.

[0068] As shown in Fig. 9, the sensor element 210 has a substantially rectangular planar shape when viewed from the Z-axis direction. The base 220 of the sensor element has a structure in which two bases 20 shown in Fig. 4 are connected in the Y-axis direction. Like the base 220, the insulating film 230a also has a structure in which two insulating films 30a shown in Fig. 4 are connected in the Y-axis direction. Although not shown in Fig. 9, the insulating films below the insulating film 230a (corresponding to the insulating films 30b and 30c shown in Fig. 4) also have a planar shape similar to that of the insulating film 230a.

[0069] The holding portion 212 of the sensor element 210 includes the insulating film peripheral portion 236 of the insulating film 230a, the base 220, and the like. Two first openings 13 are formed in the holding portion 212 with a gap in the Y-axis direction, and a sensitive film 60 is disposed in each of the first openings 13. The gap between the two first openings 13 is not particularly limited, and for example, in the sensor element 210, four holes 37 arranged in the second direction D2 (Y-axis direction) may be arranged at approximately equal intervals. Alternatively, the four holes 37 arranged in the second direction D2 may have a central gap L3 that is either wider or narrower than the gaps L4 on both sides.

[0070] 9 are electrically connected to the ends of the electrodes 50a and 50b (see FIG. 5) via through holes at the peripheral edge 214 of the holding part 212. Similarly to the electrode pad parts 271a and 271b, the heat source pad parts 272a and 272b shown in FIG. 9 are also electrically connected to the lead-out parts 42 and 43 via through holes at the peripheral edge 214 of the holding part 212.

[0071] As shown in Fig. 9, the electrode pad portions 271a, 271b are both disposed in the peripheral portion 214 of the first opening 13 of the holder 212, in a peripheral non-corner portion 214a excluding the corner portion 211 of the sensor element 210. In Fig. 9, the peripheral non-corner portion 214a is emphasized with a dot pattern for ease of understanding. Note that the corner portion 211, peripheral portion 214, peripheral non-corner portion 214a, etc. of the sensor element 210 are defined in the same manner as the corner portion 11, peripheral portion 14, peripheral non-corner portion 14a of the sensor element 10.

[0072] 9, the heat source pad portions 272a, 272b are also arranged in the peripheral non-corner portion 214a, similar to the electrode pad portions 271a, 271b. In the sensor element 210, the electrode pad portions 271a, 271b and the heat source pad portions 272a, 272b may be arranged symmetrically or asymmetrically with respect to the center position of the sensor element 10 along the Y axis.

[0073] 9, in the sensor element 210, four pad portions 271b, 272b of the eight pad portions are arranged along the second direction D2 (Y-axis direction). The remaining four pad portions 271a, 272a of the eight pad portions are arranged along the second direction D2 (Y-axis direction) with the other pad portions 271b, 272b sandwiching the center position of the sensor element 10 in the X-axis direction.

[0074] When three or more pad portions 271b, 272b are arranged along the second direction D2 like the sensor element 210, it is preferable that the first length L1 (center-to-center distance) of any two of the pad portions 271b, 272b arranged along the second direction D2 is 60% or less of the element length L2. The same applies to the pad portions 271a, 272a. By concentrating and arranging all of the pad portions 271b, 272b, 271a, 272a in an area that is equal to or smaller than a predetermined ratio of the element length L2, it is possible to effectively prevent characteristic fluctuations of the sensor element 210 due to deformation of the substrate, even in a sensor element 210 with a long element length L2.

[0075] 2, the sensor element 210 shown in Fig. 9 is connected to a substrate via at least the electrode pad portions 271a, 271b with the multiple pairs of electrode pad portions 271a, 271b facing the substrate side. The substrate on which the sensor element 210 is mounted has substrate pad portions (see Fig. 8) corresponding to the electrode pad portions 271a, 271b and the heat source pad portions 272a, 272b, and the electrode pad portions 271a, 271b and the heat source pad portions 272a, 272b are connected to the substrate pad portions.

[0076] In addition, the gas sensor having the sensor element 210 has the same effects as the gas sensor 101 according to the first embodiment in terms of the commonalities with the gas sensor 101.

[0077] Third embodiment Fig. 10 is a schematic perspective view showing a sensor element 310 included in the gas sensor according to the third embodiment. The sensor element 310 according to the third embodiment differs from the sensor element 210 shown in Fig. 9 in that it has a dummy pad 373, but is otherwise similar to the sensor element 210. Therefore, the description of the sensor element 310 will focus on the differences from the sensor element 210, and a description of the commonalities with the sensor element 210 according to the second embodiment will be omitted.

[0078] 10, the dummy pad portion 373 of the sensor element 310, like the other pad portions 271a, 271b, 272a, and 272b, is arranged in a peripheral non-corner portion 214a of the peripheral portion 214 of the holding portion 212, excluding the corner portion 211 of the sensor element 310. The dummy pad portion 373 is provided on the surface of the insulating film peripheral portion 236 of the insulating film 230a on the first direction D1 side, and is insulated from other conductive portions of the peripheral portion 214 of the sensor element 310 (for example, the ends of the electrodes 50a and 50b and the lead portions 42 and 43 (see FIG. 4)).

[0079] The sensor element 310 is connected to the substrate via the electrode pad portions 271a, 271b, heat source pad portions 272a, 272b, and dummy pad portion 373, with the electrode pad portions 271a, 271b, heat source pad portions 272a, 272b, and dummy pad portion 373 facing the substrate side. The substrate on which the sensor element 310 is mounted has substrate pad portions (see FIG. 8) corresponding to the electrode pad portions 271a, 271b, heat source pad portions 272a, 272b, and dummy pad portion 373, respectively.

[0080] The dummy pad portion 373, like the pad portions 271a, 271b, 272a, and 272b, is formed on the insulating film peripheral portion 236 by a method such as plating, lift-off, or metal paste printing. The dummy pad portion 373 is electrically insulated from other portions of the sensor element 310 and does not receive power from the substrate, but contributes to fixing the sensor element 310 to the substrate.

[0081] 10, the dummy pad portion 373 is disposed in an inter-membrane portion 314b of the peripheral non-corner portion 214a, which is a portion between two sensitive films 60 in the Y-axis direction. The inter-membrane portion 314b is the portion of the insulating film peripheral portion 236 that is farthest from the corner portion 211. Therefore, by disposing the dummy pad portion 373 in the inter-membrane portion 314b, when the sensor element 310 is mounted on a substrate, the bonding strength between the sensor element 310 and the substrate can be increased while effectively preventing the problem of stress caused by deformation of the substrate 80 being transmitted to the sensor element 310. Note that in FIG. 10, the inter-membrane portion 314b is highlighted with a dot pattern for ease of understanding.

[0082] In addition, the gas sensor having the sensor element 310 has the same effects as the gas sensor having the sensor element 310.

[0083] Fourth embodiment 11 is a schematic perspective view showing a sensor element 410 included in the gas sensor according to the fourth embodiment. The sensor element 410 according to the fourth embodiment differs from the sensor element 210 shown in FIG. 9 in that the electrode pad portion 471a and the heat source pad portion 472a are all disposed in the inter-membrane portion 414b, but is otherwise similar to the sensor element 210. Therefore, the description of the sensor element 410 will focus on the differences from the sensor element 210, and a description of the commonalities with the sensor element 210 according to the second embodiment will be omitted.

[0084] 11, similar to the sensor element 210, the sensor element 410 has a plurality of sensitive films 60, a plurality of pairs (two pairs in the embodiment) of electrodes 50a, 50b (see FIG. 4) corresponding to the respective sensitive films 60, and at least a plurality of pairs (two pairs in the embodiment) of electrode pad portions 471a, 471b electrically connected to the plurality of pairs (two pairs in the embodiment) of electrodes 50a, 50b. Also, although some parts are not shown in FIG. 11 because they are internal structures, the sensor element 410 has a plurality of (two in the embodiment) heat sources 40 corresponding to the respective sensitive films 60, and at least a plurality of pairs (two pairs in the embodiment) of heat source pad portions 472a, 472b electrically connected to the heat sources 40.

[0085] 11, in the sensor element 410, the size of the sensitive film 60 and the first opening 13 in which the sensitive film 60 is disposed is similar to that of the sensor element 210 shown in FIG. 9. On the other hand, in the sensor element 410, the width W1 from the outer edge of the hole 37 in the insulating film 430a to the element outer edge 410a is narrower than that of the sensor element 210. Therefore, in the sensor element 410, the planar shapes of the insulating film peripheral portion 436 and the base 420 are different from those of the sensor element 210, and when viewed from the Z-axis direction, the outer shapes of the insulating film peripheral portion 436 and the base 420 are smaller than those of the insulating film peripheral portion 236 and the base 220 shown in FIG.

[0086] 11, the electrode pad portions 471a, 471b and the heat source pad portions 472a, 472b are all arranged in peripheral non-corner portions 414a that are part of the peripheral portion 414 of the first opening 13 of the holder 412 and exclude the corner portions 411 of the sensor element 410. Furthermore, the electrode pad portions 471a, 471b and the heat source pad portions 472a, 472b are all arranged in inter-membrane portions 414b that are parts of the peripheral non-corner portions 414a that are between the multiple sensitive membranes 60 in the Y-axis direction.

[0087] Similar to the sensor element 210 shown in FIG. 9, the sensor element 410 shown in FIG. 11 is connected to the substrate via at least the electrode pad portions 271a, 271b and the heat source pad portions 472a, 472b, with the multiple pairs of electrode pad portions 471a, 471b and the heat source pad portions 472a, 472b facing the substrate side.

[0088] By disposing the electrode pad portions 471a, 471b and the heat source pad portions 472a, 472b in the inter-membrane portion 414b, the width W1 from the outer edge of the hole 37 in the insulating film 430a to the element outer edge 410a can be made narrower than that of the sensor element 210, which has pad portions disposed in this portion. Therefore, such a sensor element 410 is advantageous in terms of miniaturization. Furthermore, the sensor element 410 can increase the areas of the electrode pad portions 471a, 471b and the heat source pad portions 472a, 472b while avoiding an increase in the outer shape of the sensor element 410, thereby increasing the bonding strength to the substrate.

[0089] In addition, the gas sensor having the sensor element 410 has the same effects as the gas sensor having the sensor element 210 according to the second embodiment.

[0090] Example The above-described gas sensor 101 will be described in more detail below with reference to examples, but the technical scope of the gas sensor 101 is not limited to these examples.

[0091] (sample) 12A and 12B are perspective views showing sensor elements used in the gas sensors according to the example and the comparative example. The gas sensor 101 according to the example shown in Fig. 12A uses the same sensor element 10 and substrate 80 as the gas sensor 101 according to the first embodiment described with reference to Fig. 2 and the like.

[0092] Four types of samples of the gas sensor 101 according to the embodiment were prepared, each having a different first length L1, which is the center-to-center distance between the pad portions 72a and 71a or the pad portions 71b and 72b. The first length L1 of the prepared samples was 13%, 30%, 47%, and 63% of the element length L2. In each sample, the pad portions 72a, 71a, 71b, and 72b were arranged in the peripheral non-corner portion 14a.

[0093] 12(b), the gas sensor 901 according to the comparative example had electrode pad portions 971a, 971b and heat source pad portions 972a, 972b arranged at the corners of the sensor element 910, on the peripheral edge 914 of the sensor element 910. In the sample according to the comparative example, the first length L1, which is the center-to-center distance between the pad portions 972a, 971a or the pad portions 971b, 972b, was 83% of the element length L2. The gas sensor 901 is similar to the gas sensor 101 according to the example, except for the arrangement of the electrode pad portions 971a, 971b and the heat source pad portions 972a, 972b and the arrangement of the substrate pad portions on the substrate 980.

[0094] (evaluation) For each sample of the example and comparative example, a certain amount of warping was induced in the substrate 80, 980 of the gas sensor 101, 901, and the deformation (ΔZ direction displacement) occurring in the sensor element 10, 910 was measured. In Fig. 13, the horizontal axis represents the first length L1 of each sample (ratio to the element length L2), and the ΔZ direction displacement (vertical axis) of each sample is plotted. Note that the value of the ΔZ direction displacement (vertical axis) in Fig. 13 is a relative value (dimensionless).

[0095] 13, it was confirmed that in the example in which the pad portions 72a, 71a, 71b, and 72b are arranged in the peripheral non-corner portion 14a, the amount of deformation of the sensor element 10 when a predetermined warpage occurs in the substrate 80 is smaller than in the comparative example in which the pad portions 972a, 971a, 971b, and 972b are arranged in the corner portion. Furthermore, when comparing the examples, the shorter the first length L1 of the sample, the smaller the amount of deformation of the sensor element 10. Furthermore, by setting the first length L1 to 60% or less of the element length L2, a deformation suppression effect of approximately 20% or more was observed compared to the comparative example, and by setting the first length L1 to 20% or less of the element length L2, a deformation suppression effect of approximately 90% or more was observed compared to the comparative example.

[0096] The gas sensor 101 and sensor elements 10, 210, 310, and 410 according to the present disclosure have been described above using embodiments and examples. However, it goes without saying that the gas sensor according to the present disclosure includes many other embodiments and variations. For example, the sensor elements 10, 210, 310, and 410 may have three or more sensitive films. Furthermore, in the embodiments, the electrode pads 71a and 71b and the heat source pads 72a and 72b are disposed near the center in the second direction D2. However, the pads may also be disposed near one of the corners 11.

[0097] 2 and the like, the electrode pad portions 71a, 71b and the heat source pad portions 72a, 72b are mounted on the substrate 80 in a position facing the substrate 80, but in a different manner, only the electrode pad portions 71a, 71b may be mounted in a position facing the substrate 80. For example, the electrode pad portions 71a, 71b facing the substrate 80 may be connected to the substrate 80 by flip bonding, and the heat source pads facing in the other direction may be connected to the substrate 80 by wire bonding or the like. [Explanation of symbols]

[0098] 101...Gas sensor 10, 210, 310, 410, 910...sensor element 410a...Outer edge of element 11, 211, 411...Corner 12, 212, 412...holding part 13...First opening 14, 214, 414, 914...periphery 14a, 214a, 414a...peripheral non-corner part 20, 220, 420...base 22...Base periphery 30a, 30b, 30c, 230a, 430a...insulating film 31...insulating film main body 32...insulating film beam portion 36, 236, 436...Insulating film periphery 37...hole 37a...Outer edge extension 40…Heat source 41...Heat source body 42, 43...Drawer part 50a, 50b...electrode 60...Sensitive membrane 60a...center 61...Sensor membrane main body 62...Sensor membrane beam section 71a, 71b, 271a, 271b, 471a, 471b, 971a, 971b...electrode pad section 72a, 72b, 272a, 272b, 472a, 472b, 972a, 972b...heat source pad section 80...Substrate 80a...Mounting surface 81...Board pad section D1…first direction D2…Second direction L1...first length L2: Element length L3, L4… interval W1…Width 314b, 414b...intermembrane part 373...Dummy pad section

Claims

1. a sensor element including a frame-shaped holding portion, a sensitive membrane disposed in a first opening on a first direction side of the holding portion, and a pair of electrodes connected to the sensitive membrane; a substrate on which the sensor element is mounted, the sensor element is disposed in a peripheral non-corner portion of the holding portion that is a peripheral portion of the first opening, excluding corner portions of the sensor element, and has at least a pair of electrode pad portions electrically connected to a pair of the electrodes; The sensor element is a gas sensor in which the pair of electrode pad portions are connected to the substrate at least via the electrode pad portions with the electrode pad portions facing the substrate side.

2. the sensor element has a heat source for heating the sensitive film, and a heat source pad portion disposed at the non-corner peripheral portion and electrically connected to the heat source, 2. The gas sensor according to claim 1, wherein the sensor element is connected to the substrate via at least the pair of electrode pad portions and the heat source pad portion, with the pair of electrode pad portions and the heat source pad portion facing the substrate side.

3. At least two of the pair of electrode pad portions and heat source pad portions are arranged such that a center-to-center distance is a first length along a second direction perpendicular to the first direction in the peripheral edge portion, 3. The gas sensor according to claim 2, wherein the first length is 60% or less of an element length, which is the length of the sensor element in the second direction.

4. At least two of the pair of electrode pad portions and heat source pad portions are arranged such that a center-to-center distance is a first length along a second direction perpendicular to the first direction in the peripheral edge portion, 3. The gas sensor according to claim 2, wherein the first length is equal to or less than 20% of an element length, which is the length of the sensor element in the second direction.

5. the sensor element includes a plurality of the sensitive films, a plurality of pairs of the electrodes corresponding to the respective sensitive films, and at least a plurality of pairs of the electrode pad portions, all of which are disposed in the non-corner peripheral portion and electrically connected to the plurality of pairs of the electrodes; 2. The gas sensor according to claim 1, wherein the sensor element is connected to the substrate via at least the electrode pads in a position where the electrode pads face the substrate.

6. 6. The gas sensor according to claim 5, wherein the plurality of pairs of electrode pad portions are arranged in inter-membrane portions that are portions of the peripheral non-corner portion between the plurality of sensitive membranes.

7. the sensor element has a dummy pad portion disposed at the non-corner peripheral portion and insulated from other portions of the sensor element; 2. The gas sensor according to claim 1, wherein the sensor element is connected to the substrate via at least the pair of electrode pad portions and the dummy pad portion, with the pair of electrode pad portions and the dummy pad portion facing the substrate side.

8. the sensor element includes a plurality of the sensitive films, a plurality of pairs of the electrodes corresponding to the respective sensitive films, and at least a plurality of pairs of the electrode pad portions, all of which are disposed in the non-corner peripheral portion and electrically connected to the plurality of pairs of the electrodes; the sensor element has a dummy pad portion disposed in an inter-membrane portion, which is a portion between the plurality of sensitive films in the peripheral non-corner portion, and which is insulated from other portions of the sensor element; 2. The gas sensor according to claim 1, wherein the sensor element is connected to the substrate via at least the electrode pad portions and the dummy pad portions, with the plurality of pairs of the electrode pad portions and the dummy pad portions facing the substrate side.

9. a sensor element including a frame-shaped holding portion, a sensitive membrane arranged in a first opening on a first direction side of the holding portion, a pair of electrodes connected to the sensitive membrane, and a heat source that heats the sensitive membrane; a substrate on which the sensor element is mounted, the sensor element includes at least a pair of electrode pad portions that are disposed on a peripheral edge of the first opening in the holding portion and are electrically connected to the pair of electrodes, and a heat source pad portion that is disposed on the peripheral edge and is electrically connected to the heat source, the sensor element is connected to the substrate via at least the pair of electrode pad portions and the heat source pad portion, with the pair of electrode pad portions and the heat source pad portion facing the substrate side; At least two of the pair of electrode pad portions and heat source pad portions are arranged such that a center-to-center distance is a first length along a second direction perpendicular to the first direction in the peripheral edge portion, The gas sensor, wherein the first length is 60% or less of an element length, which is the length of the sensor element in the second direction.

Images